repair broken truediv test suite; memusage

the truediv test suite didn't have __backend__ so wasn't running
for every DB except in the main build.  Repaired this as well
as truediv support to preserve the right-hand side type
when casting to numeric, if the right type is already a
numeric type.

also fixed a memusage test that relies on savepoints so was
not running under gerrit runs.

Change-Id: I3be223fdf697af9c1ed61b70d621f57cbbb7a92b

1 files changed, 20 insertions, 2 deletions

diff --git a/lib/sqlalchemy/testing/suite/test_types.py b/lib/sqlalchemy/testing/suite/test_types.py
index 796de5d93..c51a66690 100644
--- a/lib/sqlalchemy/testing/suite/test_types.py
+++ b/lib/sqlalchemy/testing/suite/test_types.py
@@ -533,6 +533,8 @@ class CastTypeDecoratorTest(_LiteralRoundTripFixture, fixtures.TestBase):
 
 
 class TrueDivTest(fixtures.TestBase):
+    __backend__ = True
+
     @testing.combinations(
         ("15", "10", 1.5),
         ("-15", "10", -1.5),
@@ -576,14 +578,30 @@ class TrueDivTest(fixtures.TestBase):
         eq_(
             connection.scalar(
                 select(
-                    literal_column(left, type_=Numeric())
-                    / literal_column(right, type_=Numeric())
+                    literal_column(left, type_=Numeric(10, 2))
+                    / literal_column(right, type_=Numeric(10, 2))
                 )
             ),
             decimal.Decimal(expected),
         )
 
     @testing.combinations(
+        ("5.52", "2.4", 2.3), argnames="left, right, expected"
+    )
+    def test_truediv_float(self, connection, left, right, expected):
+        """test #4926"""
+
+        eq_(
+            connection.scalar(
+                select(
+                    literal_column(left, type_=Float())
+                    / literal_column(right, type_=Float())
+                )
+            ),
+            expected,
+        )
+
+    @testing.combinations(
         ("5.52", "2.4", "2.0"), argnames="left, right, expected"
     )
     def test_floordiv_numeric(self, connection, left, right, expected):